If we've learned anything so far, it's that the body clock is wound generally to correspond to light and dark. When it starts to get dark at night, the brain tells the body it's time for a rest by releasing melatonin into the bloodstream. So, what happens when you literally flip the (light) switch in the evening?
Artificial light can send mixed signals. Yes, a small and strategically located night-light may be necessary for navigating from bedroom to bathroom when duty calls. But other lights could throw your body clock into disarray. That includes illumination coming from a television, computer or smartphone. Many people like to wind down for the night by watching the ol' boob tube -- or streaming entertainment through their computers and tablets. If you bring those devices, and the artificial light that they give off, into bed, however, you may be tricking your brain into thinking it should stay awake [source: Klein].